import httpx

from .settings import settings


def downstream_client(request_id: str) -> httpx.AsyncClient:
    """An httpx.AsyncClient preconfigured with the 3s downstream timeout and
    the X-Request-Id header forwarded, per phase-0-base-project-spec.md §9 --
    this header is the only correlation mechanism that exists in Phase 0."""
    return httpx.AsyncClient(
        timeout=settings.downstream_timeout_seconds,
        headers={"X-Request-Id": request_id},
    )